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8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15#include <linux/security.h>
16#include <linux/eventpoll.h>
17#include <linux/rcupdate.h>
18#include <linux/mount.h>
19#include <linux/capability.h>
20#include <linux/cdev.h>
21#include <linux/fsnotify.h>
22#include <linux/sysctl.h>
23#include <linux/lglock.h>
24#include <linux/percpu_counter.h>
25#include <linux/percpu.h>
26#include <linux/hardirq.h>
27#include <linux/task_work.h>
28#include <linux/ima.h>
29
30#include <linux/atomic.h>
31
32#include "internal.h"
33
34
35struct files_stat_struct files_stat = {
36 .max_files = NR_FILE
37};
38
39DEFINE_STATIC_LGLOCK(files_lglock);
40
41
42static struct kmem_cache *filp_cachep __read_mostly;
43
44static struct percpu_counter nr_files __cacheline_aligned_in_smp;
45
46static void file_free_rcu(struct rcu_head *head)
47{
48 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
49
50 put_cred(f->f_cred);
51 kmem_cache_free(filp_cachep, f);
52}
53
54static inline void file_free(struct file *f)
55{
56 percpu_counter_dec(&nr_files);
57 file_check_state(f);
58 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
59}
60
61
62
63
64static long get_nr_files(void)
65{
66 return percpu_counter_read_positive(&nr_files);
67}
68
69
70
71
72unsigned long get_max_files(void)
73{
74 return files_stat.max_files;
75}
76EXPORT_SYMBOL_GPL(get_max_files);
77
78
79
80
81#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
82int proc_nr_files(ctl_table *table, int write,
83 void __user *buffer, size_t *lenp, loff_t *ppos)
84{
85 files_stat.nr_files = get_nr_files();
86 return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
87}
88#else
89int proc_nr_files(ctl_table *table, int write,
90 void __user *buffer, size_t *lenp, loff_t *ppos)
91{
92 return -ENOSYS;
93}
94#endif
95
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103
104
105
106struct file *get_empty_filp(void)
107{
108 const struct cred *cred = current_cred();
109 static long old_max;
110 struct file *f;
111 int error;
112
113
114
115
116 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
117
118
119
120
121 if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
122 goto over;
123 }
124
125 f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
126 if (unlikely(!f))
127 return ERR_PTR(-ENOMEM);
128
129 percpu_counter_inc(&nr_files);
130 f->f_cred = get_cred(cred);
131 error = security_file_alloc(f);
132 if (unlikely(error)) {
133 file_free(f);
134 return ERR_PTR(error);
135 }
136
137 INIT_LIST_HEAD(&f->f_u.fu_list);
138 atomic_long_set(&f->f_count, 1);
139 rwlock_init(&f->f_owner.lock);
140 spin_lock_init(&f->f_lock);
141 eventpoll_init_file(f);
142
143 return f;
144
145over:
146
147 if (get_nr_files() > old_max) {
148 pr_info("VFS: file-max limit %lu reached\n", get_max_files());
149 old_max = get_nr_files();
150 }
151 return ERR_PTR(-ENFILE);
152}
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168
169struct file *alloc_file(struct path *path, fmode_t mode,
170 const struct file_operations *fop)
171{
172 struct file *file;
173
174 file = get_empty_filp();
175 if (IS_ERR(file))
176 return file;
177
178 file->f_path = *path;
179 file->f_inode = path->dentry->d_inode;
180 file->f_mapping = path->dentry->d_inode->i_mapping;
181 file->f_mode = mode;
182 file->f_op = fop;
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189
190 if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {
191 file_take_write(file);
192 WARN_ON(mnt_clone_write(path->mnt));
193 }
194 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
195 i_readcount_inc(path->dentry->d_inode);
196 return file;
197}
198EXPORT_SYMBOL(alloc_file);
199
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207
208static void drop_file_write_access(struct file *file)
209{
210 struct vfsmount *mnt = file->f_path.mnt;
211 struct dentry *dentry = file->f_path.dentry;
212 struct inode *inode = dentry->d_inode;
213
214 put_write_access(inode);
215
216 if (special_file(inode->i_mode))
217 return;
218 if (file_check_writeable(file) != 0)
219 return;
220 __mnt_drop_write(mnt);
221 file_release_write(file);
222}
223
224
225
226static void __fput(struct file *file)
227{
228 struct dentry *dentry = file->f_path.dentry;
229 struct vfsmount *mnt = file->f_path.mnt;
230 struct inode *inode = file->f_inode;
231
232 might_sleep();
233
234 fsnotify_close(file);
235
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237
238
239 eventpoll_release(file);
240 locks_remove_flock(file);
241
242 if (unlikely(file->f_flags & FASYNC)) {
243 if (file->f_op && file->f_op->fasync)
244 file->f_op->fasync(-1, file, 0);
245 }
246 ima_file_free(file);
247 if (file->f_op && file->f_op->release)
248 file->f_op->release(inode, file);
249 security_file_free(file);
250 if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
251 !(file->f_mode & FMODE_PATH))) {
252 cdev_put(inode->i_cdev);
253 }
254 fops_put(file->f_op);
255 put_pid(file->f_owner.pid);
256 if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
257 i_readcount_dec(inode);
258 if (file->f_mode & FMODE_WRITE)
259 drop_file_write_access(file);
260 file->f_path.dentry = NULL;
261 file->f_path.mnt = NULL;
262 file->f_inode = NULL;
263 file_free(file);
264 dput(dentry);
265 mntput(mnt);
266}
267
268static LLIST_HEAD(delayed_fput_list);
269static void delayed_fput(struct work_struct *unused)
270{
271 struct llist_node *node = llist_del_all(&delayed_fput_list);
272 struct llist_node *next;
273
274 for (; node; node = next) {
275 next = llist_next(node);
276 __fput(llist_entry(node, struct file, f_u.fu_llist));
277 }
278}
279
280static void ____fput(struct callback_head *work)
281{
282 __fput(container_of(work, struct file, f_u.fu_rcuhead));
283}
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295void flush_delayed_fput(void)
296{
297 delayed_fput(NULL);
298}
299
300static DECLARE_WORK(delayed_fput_work, delayed_fput);
301
302void fput(struct file *file)
303{
304 if (atomic_long_dec_and_test(&file->f_count)) {
305 struct task_struct *task = current;
306
307 file_sb_list_del(file);
308 if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
309 init_task_work(&file->f_u.fu_rcuhead, ____fput);
310 if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
311 return;
312
313
314
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316
317
318 }
319
320 if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
321 schedule_work(&delayed_fput_work);
322 }
323}
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332
333void __fput_sync(struct file *file)
334{
335 if (atomic_long_dec_and_test(&file->f_count)) {
336 struct task_struct *task = current;
337 file_sb_list_del(file);
338 BUG_ON(!(task->flags & PF_KTHREAD));
339 __fput(file);
340 }
341}
342
343EXPORT_SYMBOL(fput);
344
345void put_filp(struct file *file)
346{
347 if (atomic_long_dec_and_test(&file->f_count)) {
348 security_file_free(file);
349 file_sb_list_del(file);
350 file_free(file);
351 }
352}
353
354static inline int file_list_cpu(struct file *file)
355{
356#ifdef CONFIG_SMP
357 return file->f_sb_list_cpu;
358#else
359 return smp_processor_id();
360#endif
361}
362
363
364static inline void __file_sb_list_add(struct file *file, struct super_block *sb)
365{
366 struct list_head *list;
367#ifdef CONFIG_SMP
368 int cpu;
369 cpu = smp_processor_id();
370 file->f_sb_list_cpu = cpu;
371 list = per_cpu_ptr(sb->s_files, cpu);
372#else
373 list = &sb->s_files;
374#endif
375 list_add(&file->f_u.fu_list, list);
376}
377
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386void file_sb_list_add(struct file *file, struct super_block *sb)
387{
388 lg_local_lock(&files_lglock);
389 __file_sb_list_add(file, sb);
390 lg_local_unlock(&files_lglock);
391}
392
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398
399
400void file_sb_list_del(struct file *file)
401{
402 if (!list_empty(&file->f_u.fu_list)) {
403 lg_local_lock_cpu(&files_lglock, file_list_cpu(file));
404 list_del_init(&file->f_u.fu_list);
405 lg_local_unlock_cpu(&files_lglock, file_list_cpu(file));
406 }
407}
408
409#ifdef CONFIG_SMP
410
411
412
413
414
415#define do_file_list_for_each_entry(__sb, __file) \
416{ \
417 int i; \
418 for_each_possible_cpu(i) { \
419 struct list_head *list; \
420 list = per_cpu_ptr((__sb)->s_files, i); \
421 list_for_each_entry((__file), list, f_u.fu_list)
422
423#define while_file_list_for_each_entry \
424 } \
425}
426
427#else
428
429#define do_file_list_for_each_entry(__sb, __file) \
430{ \
431 struct list_head *list; \
432 list = &(sb)->s_files; \
433 list_for_each_entry((__file), list, f_u.fu_list)
434
435#define while_file_list_for_each_entry \
436}
437
438#endif
439
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444
445
446
447void mark_files_ro(struct super_block *sb)
448{
449 struct file *f;
450
451 lg_global_lock(&files_lglock);
452 do_file_list_for_each_entry(sb, f) {
453 if (!S_ISREG(file_inode(f)->i_mode))
454 continue;
455 if (!file_count(f))
456 continue;
457 if (!(f->f_mode & FMODE_WRITE))
458 continue;
459 spin_lock(&f->f_lock);
460 f->f_mode &= ~FMODE_WRITE;
461 spin_unlock(&f->f_lock);
462 if (file_check_writeable(f) != 0)
463 continue;
464 __mnt_drop_write(f->f_path.mnt);
465 file_release_write(f);
466 } while_file_list_for_each_entry;
467 lg_global_unlock(&files_lglock);
468}
469
470void __init files_init(unsigned long mempages)
471{
472 unsigned long n;
473
474 filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
475 SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
476
477
478
479
480
481
482 n = (mempages * (PAGE_SIZE / 1024)) / 10;
483 files_stat.max_files = max_t(unsigned long, n, NR_FILE);
484 files_defer_init();
485 lg_lock_init(&files_lglock, "files_lglock");
486 percpu_counter_init(&nr_files, 0);
487}
488